A hand-held grinder has a main body portion having a substantially cylindrical body shape that receives an electric motor therein, the main body portion is used as a grip portion, which is held by a user for a grinding operation, etc. A speed reduction portion is provided at a front portion of the main body portion for reducing the rotational output of the electric motor by a bevel gear train and outputting it in a perpendicular direction. For this purpose, a spindle on an output side of the speed reduction portion extends perpendicular to a motor shaft. A circular grinding stone (wheel) is attached to the spindle. In general, a substantially semi-circumferential range on a rear side of the grinding stone (a user side) is covered with a cover for preventing powder dust or the like (hereinafter simply referred to as dust), which is generated during a grinding operation, from scattering towards the user.
This cover for the grinding stone can be removed for the convenience of an exchanging operation, etc., as disclosed, for example, in a patent document listed below and can change its position by rotating about an axis of the spindle within an appropriate range in consideration of the working postures of a user, etc. The positional change of this grinding stone cover can be made by loosening fixing screws, etc.
Patent Document 1: Japanese Laid-Open Utility Model Publication No. 56-28844
However, this kind of grinding stone cover has accompanied the following problems. As described above, because it is constructed to enable the position of the grinding stone to change about an axis of the spindle to an arbitrary position by loosening a fixing screw, a problem may be caused that cutting chips scatter towards a user if the position is adjusted, when it is opened toward the user at a large angle, and therefore, the construction for enabling the position to be changed to an arbitrary position (a position adjustment function) may rather impair the usability from a viewpoint of prevention of dust from scattering.
Further, if the tightening of the fixing screw after the positional adjustment is weak, the grinding stone cover may, for example, contact the other parts so that the position may be largely displaced in an opening direction, resulting to bring it into a condition so that the a dust scattering prevention function is impaired in some cases.
Thus, there is a need in the art for a dust scattering prevention function to be reliably executed without substantially impairing a position adjustment function of a grinding cover.